Ministers have signalled their backing for controversial plans to build an incinerator on the edge of King's Lynn, which could dash the hopes of those seeking to get a political U-turn.

Supporters of the proposals last night insisted the government is four square behind their approach after receiving a ministerial letter from communities secretary Eric Pickles deputy Andrew Stunell stating that it fits in with coalition policies to become the 'greenest government ever'.

Meanwhile a second letter sent to South-West Norfolk MP Elizabeth Truss from waste management minister Lord Henley stated that the government had no plans to look again at incinerators and would not interfere in Norfolk County Council's decision.

In his letter, sent on March 24, Mr Stunell the Lib Dem junior minister, expressed his 'congratulations' to the county council for its achievement in awarding the PFI contract.

'This coalition government has the ambition to achieve an eco-friendly economy and to become the greenest government ever,' he wrote. 'Your council's application of the PFI to increase waste recycling rates, generate energy from waste and do so on both an environmentally and value for money basis is commendable.'

But last night South-West Norfolk MP Elizabeth Truss, sho plans to lobby ministers about the public's concerns over the plans, said she would not throw in the towel over the issue, while North-West Norfolk MP Henry Bellingham said the government had only been given half of the story.

The county council's ruling cabinet has found itself in the firing line after agreeing to award a contract for to build an energy from waste plant on the Saddlebow Industrial Estate to Anglo-US firm Cory Wheelabrator.

There has been growing anger at the decision, which followed a borough wide poll by West Norfolk Council in which more than 65,000 people vote against the proposal. That poll, and what account should be taken of it, is at the heart of an increasingly bitter row between borough and county council Conservatives in West Norfolk.

But in his letter Lord Henley pointed out that the county council had held a 'future of Norfolk' public consultation with every household in the county to get their views on how to treat waste in the future and this was an 'integral and influential part of the consultation' process which led to the selection of the energy from waste proposal.

'With regards to the referendum...neither Norfolk County Council nor the preferred bidder took part in the referendum process,' Lord Henley wrote. 'Norfolk County Council as the strategic authority for the whole of Norfolk, will encourage all residents to engage in the planning process through the consultation. I hope this reassures you that our approach towards Norfolk County Council does not go 'against the principle of localism'.

County council leader Derrick Murphy, who wrote to communities secretary Eric Pickles to inform him of the decision and the council's wish to conclude the contract as soon as possible, said he was heartened by the response Mr Stunell.

The exchange, comes as landfill taxes for rubbish increased to �56 per tonne, which means the total bill for the council will increase to nearly �13m, the same amount as the authority spends on the library service.

Supporters believe the incinerator will help save counciltaxpayers more than �8m a year and boost recycling by 20pc, but critics are concerned about the health risks associated with incinerators, and also believe that rising recycling rates could mean that Norfolk has to import waste from elsewhere to keep the plant running.

Mr Murphy who is at loggerheads with his West Norfolk borough council counterpart Nick Daubney over the issue, said the letters demonstrated that the coalition government was behind the approach being pursued by the council. He also questioned why the borough council was resisting the plans despite previously agreeing to a proposal by Palm Paper to build another incinerator in the same site.

But Mr Daubney said County Hall was wrong to ignore the weight of public opinion and repeated his calls for all councils to work together on a greener waste strategy.

Mr Murphy said: 'The letters struck me as a pretty strong endorsement of what we are doing. I wrote to Eric Pickles to make absolutely sure given the concerns levelled about this, that the county council was doing the write thing, and it's clear from this that the answer is very much so. Both Defra and the Department for Communities and Local Government have been in constant communication with the county council for the whole period of time.

'If I was going to spend �53,000 on this poll I would be asking if anyone has checked with the government whether this would have any impact on the procurement process,' he added.

Last week anti-incinerator campaigners seized on a remark by David Cameron during prime minister's questions stating that it was 'very important local communities have their say' on planning matters.

Politically, some are also pinning their hopes on the possibility of lobbying by the two MPs to secure a climbdown at Westminster.

Mr Daubney said he was gobsmacked by County Hall's decision to ignore the strength of public opinion.

'I don't know the question that was asked of Eric Pickles, but I heard what David Cameron said and it didn't leave much doubt that people's views should be taken into account.

'Palm Paper made a proper application for burning their own waste using gas to burn it, it's a total red herring,' Mr Daubney added.

Ms Truss, said: 'The government may say that, but I'm not happy with that and I do not agree with the end result, that's the job of an MP,' she said. 'People assail me on an almost daily basis on the about this proposed incinerator. My own view is that anything is possible. If there is substantial public disquiet about these proposals, there is always a way to change them.'

Mr Bellingham said the council had failed to spell out to the government the strength of feeling against the incinerator.

'The county council has been devious,' he said. 'Local people in this area have spoken in the most extraordinary way. There is overwhelming opposition to it. I am going to be leaving Eric Pickles and Andrew Stunell in no doubt about the fact that this is deeply unpopular.'